package main

import (
	"flag"
	"fmt"
	"io"
	"os"
	"path"
	"strconv"

	"github.com/chrislusf/weed-fs/go/glog"
	"github.com/chrislusf/weed-fs/go/storage"
	"github.com/chrislusf/weed-fs/go/util"
)

var (
	fixVolumePath       = flag.String("dir", "/tmp", "data directory to store files")
	fixVolumeCollection = flag.String("collection", "", "the volume collection name")
	fixVolumeId         = flag.Int("volumeId", -1, "a volume id. The volume should already exist in the dir. The volume index file should not exist.")
)

/*
This is to resolve an one-time issue that caused inconsistency with .dat and .idx files.
1. fix the .dat file, a new .dat_fixed file will be generated.
	go run fix_dat.go -volumeId=9 -dir=/Users/chrislu/Downloads
2. move the original .dat and .idx files to some backup folder, and rename .dat_fixed to .dat file
    mv 9.dat_fixed 9.dat
3. fix the .idx file with the "weed fix"
	weed fix -volumeId=9 -dir=/Users/chrislu/Downloads
*/
func main() {
	flag.Parse()
	fileName := strconv.Itoa(*fixVolumeId)
	if *fixVolumeCollection != "" {
		fileName = *fixVolumeCollection + "_" + fileName
	}
	indexFile, err := os.OpenFile(path.Join(*fixVolumePath, fileName+".idx"), os.O_RDONLY, 0644)
	if err != nil {
		glog.Fatalf("Read Volume Index [ERROR] %s\n", err)
	}
	defer indexFile.Close()
	datFile, err := os.OpenFile(path.Join(*fixVolumePath, fileName+".dat"), os.O_RDONLY, 0644)
	if err != nil {
		glog.Fatalf("Read Volume Data [ERROR] %s\n", err)
	}
	defer datFile.Close()

	newDatFile, err := os.Create(path.Join(*fixVolumePath, fileName+".dat_fixed"))
	if err != nil {
		glog.Fatalf("Write New Volume Data [ERROR] %s\n", err)
	}
	defer newDatFile.Close()

	header := make([]byte, storage.SuperBlockSize)
	datFile.Read(header)
	newDatFile.Write(header)

	iterateEntries(datFile, indexFile, func(n *storage.Needle, offset int64) {
		fmt.Printf("file id=%d name=%s size=%d dataSize=%d\n", n.Id, string(n.Name), n.Size, n.DataSize)
		s, e := n.Append(newDatFile, storage.Version2)
		fmt.Printf("size %d error %v\n", s, e)
	})

}

func iterateEntries(datFile, idxFile *os.File, visitNeedle func(n *storage.Needle, offset int64)) {
	// start to read index file
	var readerOffset int64
	bytes := make([]byte, 16)
	count, _ := idxFile.ReadAt(bytes, readerOffset)
	readerOffset += int64(count)

	// start to read dat file
	offset := int64(storage.SuperBlockSize)
	version := storage.Version2
	n, rest, err := storage.ReadNeedleHeader(datFile, version, offset)
	if err != nil {
		fmt.Printf("cannot read needle header: %v", err)
		return
	}
	fmt.Printf("Needle %+v, rest %d\n", n, rest)
	for n != nil && count > 0 {
		// parse index file entry
		key := util.BytesToUint64(bytes[0:8])
		offsetFromIndex := util.BytesToUint32(bytes[8:12])
		sizeFromIndex := util.BytesToUint32(bytes[12:16])
		count, _ = idxFile.ReadAt(bytes, readerOffset)
		readerOffset += int64(count)

		if offsetFromIndex != 0 && offset != int64(offsetFromIndex)*8 {
			//t := offset
			offset = int64(offsetFromIndex) * 8
			//fmt.Printf("Offset change %d => %d\n", t, offset)
		}

		fmt.Printf("key: %d offsetFromIndex %d n.Size %d sizeFromIndex:%d\n", key, offsetFromIndex, n.Size, sizeFromIndex)

		padding := storage.NeedlePaddingSize - ((sizeFromIndex + storage.NeedleHeaderSize + storage.NeedleChecksumSize) % storage.NeedlePaddingSize)
		rest = sizeFromIndex + storage.NeedleChecksumSize + padding

		func() {
			defer func() {
				if r := recover(); r != nil {
					fmt.Println("Recovered in f", r)
				}
			}()
			if err = n.ReadNeedleBody(datFile, version, offset+int64(storage.NeedleHeaderSize), rest); err != nil {
				fmt.Printf("cannot read needle body: offset %d body %d %v\n", offset, rest, err)
			}
		}()

		if n.Size <= n.DataSize {
			continue
		}
		visitNeedle(n, offset)

		offset += int64(storage.NeedleHeaderSize) + int64(rest)
		//fmt.Printf("==> new entry offset %d\n", offset)
		if n, rest, err = storage.ReadNeedleHeader(datFile, version, offset); err != nil {
			if err == io.EOF {
				return
			}

			fmt.Printf("cannot read needle header: %v\n", err)
			return
		}
		//fmt.Printf("new entry needle size:%d rest:%d\n", n.Size, rest)
	}

}